magaldrate (aluminum magnesium hydroxide)
Iosopan, Riopan

Available forms
Available without a prescription
Solution or suspension: 540 mg/5 ml

Indications and dosages
 Indigestion or hyperacidity caused by peptic ulcer, gastritis, peptic esophagitis, hiatal hernia. Adults: 5 to 10 ml P.O. between meals and h.s. with water.

Pharmacodynamics
Antacid action: Magaldrate neutralizes gastric acid, reducing the direct acid irritant effect. This increases gastric pH, which inactivates pepsin. Magaldrate also enhances mucosal barrier integrity and improves gastroesophageal sphincter tone.

Pharmacokinetics
Absorption: Aluminum may be absorbed systemically. Magnesium also may be absorbed, posing a risk to patients with renal failure. Absorption is unrelated to mechanism of action.
Distribution: Distribution is primarily local.
Metabolism: None.
Excretion: Excreted in feces; some aluminum and magnesium may appear in breast milk. Duration of action is prolonged.

Contraindications and precautions
Contraindicated in patients with severe renal disease. Use cautiously in patients with mild renal impairment.

Interactions
Drug-drug. Anticoagulants, antimuscarinics, chenodiol, chlordiazepoxide, coumadin, diazepam, digoxin, isoniazid, phenothiazines (especially chlorpromazine), phosphates, quinolones, tetracycline, vitamin A: Decreases absorption of these drugs, thus lessening their effectiveness. Separate administration times.
Enteric-coated drugs: May cause premature release of these drugs. Separate doses of magaldrate and all oral drugs by 1 to 2 hours.
Levodopa: May increase levodopa absorption, increasing risk of toxicity. Separate administration times.
Drug-herb. Melatonin: Causes additive inhibitory effects on the N-methyl-D-aspartate receptor. Discourage use together.

Adverse reactions
GI: mild constipation, diarrhea.
Metabolic: hypokalemia.

Effects on lab test results
• May increase gastrin and urine pH levels. May decrease potassium levels.

Overdose and treatment
No information available.

Special considerations
• Shake suspension well; give with small amounts of water or fruit juice.
• After administration through nasogastric tube, flush tube with water to clear it and ensure passage of drug to stomach.
• Give drug at least 1 hour apart from enteric-coated drugs.
• Monitor renal function and serum phosphate, potassium, and magnesium levels in patients with renal disease.
• Suspension contains saccharin and sorbitol.
• Most formulations contain less than 0.5 mg of sodium per teaspoon (5 ml).
Breast-feeding patients
• Some aluminum and magnesium may appear in breast milk. However, no problems have been linked to use in breast-feeding women.
Pediatric patients
• Use of drug as an antacid in children younger than age 6 requires a well-established diagnosis because children typically give vague descriptions of symptoms.

Patient education
• Caution patient to take drug only as directed and 1 or 2 hours apart from other oral medications.
• Remind patient to shake suspension well.
• Warn patient not to take more than 18 teaspoons of drug in a 24-hour period.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use